Removing odor from petroleum-based dry cleaning solvent with diglycolic acid



REMOVING ODOR FROM PETROLEUM-BASED DRY CLEANING SOLVENT WITH DIGLYCOLIC ACID No Drawing. Filed Dec. 24, 1958, Ser. No. 782,634

2 Claims. (Cl. 208-480) This invention is directed to an improvement in the art of reconditioning petroleum-based solvents which are used in commercial dry cleaning operations. Although several types of solvents are presently used in commercial dry cleaning operations, dry cleaners naphtha, a petroleum-based solvent, is the least expensive and the most commonly used.

As these naphtha drycleaning plants are now operated, a series of batches of fabrics are cleaned in a given quota of solvent which may be filtered during the cleaning operation or between the cleaning of different batches of fabrics to remove the filterable dirt therefrom. However, the unfilterable contamination in the solvent builds 7 up with the cleaning of successive batches so that ultimately the solvent has to be distilled or discarded.

One of the more diificult contaminants to remove from the solvent is the residue from perspiration deposited on the clothes. This problem is apt to be particularly severe in warm climates. Even with distillation, some of the odor of the perspiration residue distills over with the solvent and imparts a musty, unpleasant odor to the fabrics which are afterward cleaned in the solvent. The amount of this offensive perspiration residue is minute, almost infinitesimal, and cannot even be detected by chemical analysis. The problem is to remove these traces of perspiration residue from the solvent without incorporating in the solvent any foreign substance which might be detrimental when the dry cleaning solvent is re-used.

I have found that diglycolic acid removes the odor of perspiration from dry cleaners naphtha. The diglycolic acid is not soluble in dry cleaners naphtha and, hence, does not tend to contaminate the solvent. Ap-

SEaKES Patent parently, the diglycolic acid removes the odor from the solvent by absorption, adsorption, or chemical reaction. In view of the fact that the odor forming substances are present in such small amounts, it is impossible to establish any reliable theory as to the nature of the phenomenon. This invention is therefore predicated entirely on the empirical determination that glycolicacid removes objectionable odors or odor forming substances from dry cleaners naphtha.

The amount of diglycolic acid used is neither critical or important, but thorough surface contact between the naphtha and the diglycolic acid is important. This surface contact may be accomplished by agitating the solvent and the diglycolic acid together or by percolating the solvent through a body of acid or vice versa. However, I prefer first to distill the solvent, then put it through a conventional rag drier, the rags of which are impregnated with diglycolic acid. 1

This operation is preferably carried out in the followingmanner. Eight ounces of diglycolic acid are dissolved in five gallons of water. The rags are impregnated with 7 this solution and then dried, leaving the diglycolic acid on the rags. A good result is obtained by using one pound of solution for each one pound of rags which leaves il /2% diglycolic acid on the rags, based on the weight of the rags. After the solvent is distilled, it is put through the rag filter and thus exposed to the diglycolic acid which 7 is on the rags.

Having described my invention, I claim:

1. The method of improving the odor of a petroleumbased dry cleaning solvent which comprises distilling the solvent and contacting the distilled solvent with diglycolic acid.

2. The method of improving the odor of a petroleumbased dry cleaning solvent which comprises distilling the solvent, then passing the solvent through a rag filter the rags of which are impregnated with diglycolic acid.

References Cited in the file of this patent UNITED STATES PATENTS 1,633,942 Hey June 28, 1927 2,773,919 Millikan Dec. 11, 1956 FOREIGN PATENTS 518,593 France .May 27, 1921 761,862 Great Britain Nov. 21, 1956 

1. THE METHOD OF IMPROVING THE ODOR OF A PETROLEUMBASED DRY CLEANING SOLVENT WHICH COMPRISES DISTILLING THE SOLVENT AND CONTACTING THE DISTILLED SOLVENT WITH DIGLYCOLIC ACID. 